A series of images and video have captured the heart-stopping moment a boat speeds over the top of three southern right whales, just off the Bluff near Victor Harbor at about 9am on Friday, June 12.
In the dramatic vision, the boat travels at speed towards the whales who were being observed milling on the surface, leaving onlookers aghast.
The boat is being operated by a single male who appears to be oblivious of the impending danger, before he speeds over the top of the whales.
Fortunately, any contact appears to have been glancing, as the boat lurches to the left and continues at speed without stopping.
The condition of the whales is currently unknown, and they have not been spotted in the area since the day of the incident.
The incident was reported to National Park and Wildlife Service South Australia (NPWSSA) by members of the whale watching community group Encounter Whales, and the Department for Environment and Water has since investigated the incident, describing it as a "near miss."
NPWSSA rangers have since identified the boatie and reminded him to be vigilant during whale season (May to October).
NPWSSA Ranger Jon Emmett said the incident is a serious reminder to boat users to slow down, be extra vigilant and be on the lookout for whales off the southern Fleurieu coast.
"The boatie last week came within centimetres of the whales and was unaware of just how close he came to a potentially serious accident," Mr Emmett said.
"Boat and whale collisions have the potential to hurt both parties, with five anglers recently injured and rescued when they collided with a whale in waters off Tasmania.
"If a whale does emerge close to your vessel, you must slow down and navigate away from the animal."
Encounter Whales spokesperson Elizabeth Steele-Collins said it was miraculous there was no serious collision.
"Travelling at an estimated speed of 20-25 knots, the skipper of the boat was very lucky not to have been seriously injured or even killed. However, we do not know what injuries might have been sustained by any of the three whales," Ms Steele-Collins said.
"Unfortunately, shortly after, the same whales were subject to further distress when the same boat departed Kings Beach returning to the boat ramp, only to head straight back to Kings Beach again. Inadvertently travelling at speed over these whales three times.
"Sadly, this incident is not unique. Whales have been observed showing vessel strike injury and there have been a number of documented 'near miss' incidents right here in Encounter Bay in the last few years.
"While whale collisions involving injury to humans are usually documented (such as the recent collision in Tasmania only two days prior), most near-misses go unreported, and can even go unnoticed by boat occupants."
It serves as a timely reminder for boaties to be hyper-vigilant, with whale season now in full swing.
Mr Emmett said that whales disturbed may alter their migration paths and become displaced from important habitats used for resting, breeding and nursing calves.
"That's why there are regulations stipulating safe approach distances for whale-watching boats, jet skis and drones in South Australian waters," Mr Emmett said.
Ms Steele-Collins said the incident illustrates the risk that boats travelling at speed pose to themselves and to whales.
"Whales can literally pop up at any time or in any place with little to no warning," Ms Steele-Collins said.
"Waters along the coastline, and many within the entire bay area, are recognised whale corridors and aggregation areas that are frequented by these leviathans during this time.
"Southern right whales are slow swimmers and often stay close to shore. The whales are needing to rest after their long migration and are often seen floating on or just below the water's surface which can make them difficult to spot at times, a collision waiting to happen.
"Lower speed limits and extra caution are of utmost importance during whale season and especially along the well known whale corridors."
Ms Steele-Collins said the recent incident also demonstrated a need to provide further protection to whales from motorised vessels in their most vulnerable breeding and nursing area.
"There is currently no regulation preventing motorised vessels travelling at speed through the whales calving and nursery area in Encounter Bay (the core area located between Port Elliot and Goolwa Beach)," she said.
"Whale mothers and their inexperienced calves are particularly vulnerable to vessel strike. The whales need a motorised vessel-free nursery area where mothers and calves are free from disturbances.
"Where the mothers can rest and be at ease to feed and raise their young and prepare them for the long migration back to sub-Antarctic waters at the end of the season."